SpringBoot 使用RestTemplate实现调用服务

SpringBoot的搭建可以看一下我之前写的一篇博客

https://blog.csdn.net/cwr452829537/article/details/81351987

准备工作

要使用RestTemplate需要引入依赖，web依赖也可以在创建项目时选择Web -> Web

<!-- web -->
<dependency>
   <groupId>org.springframework.boot</groupId>
   <artifactId>spring-boot-starter-web</artifactId>
</dependency>

<!-- 远程调用 httpclient -->
<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpclient</artifactId>
    <version>4.5.5</version>
</dependency>

 注入RestTemplate

  首先需要在Application中加入一个RestTemplate

  
  
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import org.springframework.http.client.HttpComponentsClientHttpRequestFactory;
import org.springframework.web.client.RestTemplate;

@SpringBootApplication
public class RemoteApplication {
@Bean //必须new 一个RestTemplate并放入spring容器当中,否则启动时报错
public RestTemplate restTemplate() {
HttpComponentsClientHttpRequestFactory httpRequestFactory = new HttpComponentsClientHttpRequestFactory();
httpRequestFactory.setConnectionRequestTimeout( 30 * 1000);
httpRequestFactory.setConnectTimeout( 30 * 3000);
httpRequestFactory.setReadTimeout( 30 * 3000);
return new RestTemplate(httpRequestFactory);
}
public static void main(String[] args) {
SpringApplication.run(RemoteApplication.class, args);
}
}
  
  

 调用服务

  实体类

  
  
import com.fasterxml.jackson.annotation.JsonProperty;
import lombok.Data;

@Data
public class UserEntity {
@JsonProperty( "user_id")
private Long userId;
private String name;
private String phone;
}
  
  

  
  
import lombok.Data;

@Data
public class Result {
private Integer code;
private String message;
}
  
  

  controller

  
  
import com.cwr.remote.model.db.UserEntity;
import com.cwr.remote.model.vo.Result;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.*;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.client.RestTemplate;


@RequestMapping( "/remote")
//允许跨域访问
@CrossOrigin(origins = "*", maxAge = 3600)
@RestController
public class RemoteController {
//自动注入RestTemplate
private final RestTemplate restTemplate;

@Autowired
public RemoteController(RestTemplate restTemplate) {
this.restTemplate = restTemplate;
}

/**
* 调用远程服务添加用户信息
*
* @param userEntity 用户实体
* @return
*/
@PostMapping( "/add-user")
public Result addUser(@RequestBody UserEntity userEntity) {
HttpEntity<UserEntity> entity = new HttpEntity<>(userEntity);
ResponseEntity<Result> resultResponseEntity = this.restTemplate.exchange(
"http://xxx.xxx.xxx.xxx/user/add",
HttpMethod.POST, entity, Result.class);
if (resultResponseEntity.getStatusCode() == HttpStatus.OK) {
return resultResponseEntity.getBody();
}
return null;
}

/**
* 调用远程服务查询单个用户信息
*
* @param id 用户id
* @return
*/
@GetMapping( "/find-user-id/{id}")
public UserEntity findOne(@PathVariable Long id) {
ResponseEntity<UserEntity> resultResponseEntity = this.restTemplate.exchange(
String.format( "http://xxx.xxx.xxx.xxx/user/find-id/%s", id),
HttpMethod.GET, null, UserEntity.class);
if (resultResponseEntity.getStatusCode() == HttpStatus.OK) {
return resultResponseEntity.getBody();
}
return null;
}
}
  
  

这里详细讲一下exchange( )方法

public <T> ResponseEntity<T>

           exchange(String url, HttpMethod method, @Nullable HttpEntity<?> requestEntity, Class<T> responseType) 

•     url:请求地址，如果需要在url中带参数，使用String.format()，用%s拼接即可;
•     method:请求方式，HttpMethod是一个枚举类型，有GET、POST、DELETE等方法;
•     requestEntity:请求参数，这个主要是POST等有请求体的方法才需要，GET、DELETE等方法可以为null;
•     responseType:返回数据类型。

测试结果（我使用的是Postman）